More help continued!

[jeffwagnpete]

This photo is where the old bulkhead, stringer and rigging supports used to be, these are voids about 1/4 inch deep. Would I use matting to build up these voids. Would I just cut strips of matting about the same width, then apply, then on final layer, use a wider strip about 10 inches to cover the smaller strips.? Or would you mix polyester resin with miller fiber and apply to the voids?, then use matting to cover the mixture up?

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Heres me pointing at the stress fracture below the water line, I dont even know what to do with this, any quick explaining would help.

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Heres the same stress fracture but on the exact other side, but even worse, this one has made a cut through the structure. How would you go about by fixing this? Vaccum bag, or layering?

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[jeffwagnpete]

Hello Zach,

Thanks for your reply. I just need to know the steps of the material to use, for instance; matting first, then filler, more matting, ect.

[Zach]

Hi Jeff,

Buy a copy of Allan H Vaits "The Fiberglass Boat Repair Manual."
http://www.amazon.com/Fiberglass-Boat-R ... 0071569146

You won't need to use any microballoons, or do any vacuum bagging to make a structural repair.

Your deep grooves where the bulkheads used to go, are there because the lumps to each side is the old fiberglass tabbing that held the bulkheads in place. The woven roving (the bumpy stuff) on each side continues under the tabbing. I just grind out the old till I see the roving through the mat.

Your crack that goes all the way through the hull (I hope its not very big... use epoxy if it is...) will get ground out from both sides, meeting in the middle. You will taper the edges, 12:1 over the depth, that means half the total depth per side... then glass one side with a backer board to hold it taught. If it was me, I'd glass the outside, push a piece of 4 mil poly sheet against it and tape it off, then warp a piece of 1/8th inch plywood, card board, whatever around it. I'd then immediately go inside and glass the inside. You'll be cutting circles, or kidney beans of cloth and roving. Small to big. First piece is going to lap past everything an inch, next piece will be a 1/2 to 3/4 inch overlap on all sides, next will do the same. I use a sharpie to mark the circles... makes cool patterns when you grind it down.
squared off corners don't work very well patching a curved hull, it gives you a lot of excess to grind.

The general practice involves grinding out the bad until you get to good material with no cracks. More than likely your stress crack is a void along side a piece of roving that didn't get air rolled out. With polyester the practice is to start with a narrow strip of glass, then a wider one, and wider... so if any one piece doesn't bond the whole shooting match doesn't fall off.

Since you are using polyester resin from last years work. I would buy a new bottle of mekp on principle, it has a shelf life and time causes it to kick at different rates, requiring more by %. (I would use west systems epoxy, but that doesn't mean polyester won't work...) you'll put down a layer of mat first to have a resin rich layer right to the hull. I'd grind with 40 grit, do an acetone wipe... and at least think about wiping the area with styrene to try and get a better bond.

Since you are trying for a structural repair, I'd kick it off at max 2.5% though in practice when most folks, I included, are messing about with polyester it gets catalyzed closer to 4%. The staged vial sizes work out pretty close for pints, quarts, and gallons to just toss the whole thing in. If it is slow to kick, set up a box fan and move some air across it... and point a strong light/heat lamp at it.

The reason to do it all at once, is so that your polyester plug locks in as one piece and you get a good bond primary bond on something that can't fall loose.

You will need a nice set of scissors. You can either go to a fabric store and buy the best pair of pinking shears you can lay your hands on (30 bucks...) or buy a pair of Wiss industrials. http://bodico.com/searchresult.aspx?categoryID=200

You will want a box of large or extra large latex gloves, some 2 inch cheapo chip brushes, some mixing cups, a ribbed air roller... and a wet out bench. Take a piece of plywood, staple a trash bag around it. Wet out your pieces one at a time stacking them up as they will go into the boat. Roll the excess resin out, that means just not a super human amount of pressure, but not light... 10lbs or so? The first pass or two will push a blob of resin out of the different layers. Now take a chip brush and wet out the hole in the hull with resin. Take your wad of cloth and stuff, and stick it in place air rolling. It takes a lot of cloth to build out a hole in a boat. You'll have a depression in the middle, don't worry about it... when you glass from the inside with the back board in place outside you'll roll it out pretty fair.

Practice this... wet out a piece of cloth, stick it to something upside down. Walk away for a minute or two.
Come back... is it on the floor? You used to much resin.

You have two ounce mat, use that the first layer or two, then get some 6 ounce stuff, just so it builds thicker.
You can either add a layer of roving, followed by a layer of mat, or if the valley you've ground in the hull isn't through the roving layers, build the whole thing up with mat.

You won't use your fillers, until after you have come all the way out and are out to the finished surface height. On structural stuff I like to add enough glass that I need to come back and grind it down in the morning. You'll want to see if the resin you are using is a finishing type, or a laminating type. If it is laminating, it'll be gummy on your tools tomorrow. (Thats why folks over-catalyze... sets up rock hard, right now...) You can brush on some poly vinyl alcohol mold release as an air barrier. You can get it at west marine, but it costs the same for 8 ounces as buying a gallon online. Part All PVA is the name of the stuff...

Thats pretty much it, if you've gotta use polyester.

Epoxy is the same time involved, but you'll have more brain cells left after doing the work inside the hull...
Grind back your V 12:1
Mix up epoxy, if you are just starting out... weigh the cloth, thats how many ounces you'll need of resin unless you are wetting out plywood first. Plywood takes about 2 ounces per square foot to wet out.
1708 biaxial is the industry standard for boat repairs, its easy to work with, fast building, and structurally sound.

Epoxy is an adhesive, that means the two layers of reinforcement that are stitched together... the epoxy can span the gap and hold everything together. Mat is not required between layers. Vinylester can also work with biaxial glass... but by the book the guys that sell epoxy tell you not to use biaxial and triax with polyester. I have, goofing off making stuff with no real ill effect. (Other than lost brain cells... similar to the buffalo theory.)

In this you wet out the hull, with resin.
Wet out the glass on a table, roll the excess.
Stick it in place... Roll it again to work the air out from under the first layer.
Come back in 6-8 hours if its fast hardener and scuff it off.

Thats pretty much the gist of it.

Microballoons are pretty much junk for doing anything structural. Cabosil makes a glue paste. Ground cotton fiber, or milled glass fiber, 1/32 glass, make stuff that is bomb proof.
Everything above after microballoons, is like sanding rock candy, your concrete driveway, and granite... in that order.
I use glass balloons, as they are cheap.

Quick tip... when fairing balloons, go get some food coloring and alcohol. Wet a rag with alcohol, add food coloring. Now wipe the hull... Sand her down, and the low spots are green. (If you use green food coloring.)

Good luck, and have fun.

Zach